Steel products are widely used and have various varieties. Different standards refer to different types of steel products. There are seven main categories:

1. Classified by quality

(1) Ordinary steel (P≤0.045%, S≤0.050%) 

(2) High-quality steel (both P and S≤0.035%) 

(3) High quality steel (P≤0.035%, S≤0.030%) 

2. Classified by chemical composition

(1) Carbon steel: low carbon steel (C≤0.25%); medium carbon steel (C≤0.25-0.60%); high carbon steel (C≥0.60%). 

(2) Alloy steel: low alloy steel (total content of alloy elements ≤ 5%); medium alloy steel (total content of alloy elements > 5-10%); high alloy steel (total content of alloy elements > 10%). 

3. Classified by forming method:

(1) Forged steel (2) Cast steel (3) Hot rolled steel (4) Cold drawn steel. 

4. Classification according to metallographic structure

(1) Annealed state: hypoeutectoid steel (ferrite + pearlite); eutectoid steel (pearlite); hypereutectoid steel (pearlite + cementite); ledeburite steel (pearlite + cementite) carbon body)

(2) Normalized state: pearlitic steel; bainite steel; martensitic steel; austenitic steel. 

(3) No phase change or partial phase change. 

5. Classification by purpose

(1) Construction and engineering steel: ordinary carbon structural steel; low alloy structural steel; reinforced steel.

(2) Structural steel

(3) Tool steel: carbon tool steel; alloy tool steel; high-speed tool steel.

(4) Special performance steel: stainless acid-resistant steel; heat-resistant steel: including oxidation-resistant steel, heat-strength steel, valve steel; electric heating alloy steel; wear-resistant steel; low-temperature steel; electrical steel. 

(5) Steel for professional use: such as steel for bridges, steel for ships, steel for boilers, steel for pressure vessels, steel for agricultural machinery, etc. 

6. Comprehensive classification:

(1) Ordinary steel

(2) High-quality steel (including high-grade high-quality steel)

7. Classified by smelting method

(1) According to furnace types: a. Open hearth furnace steel b. Converter steel c. Electric furnace steel

(2) According to deoxidation: boiling steel; semi-killed steel; killed steel; special killed steel.